1. Field of the Invention
The present invention relates to a photoelectrochemical electrode for carbon dioxide conversion including a p-type copper-iron composite oxide and a photoelectrochemical device including the photoelectrochemical electrode.
2. Description of the Related Art
Solar CO2 recycling has received wide attention primarily to address global CO2 emission and to convert CO2 and water to value-added chemicals. Despite a long research history over the past four decades, the technology remains in an early stage, with low CO2 conversion efficiency and selectivity. CO2 is highly stable and has limited solubility in water, and its reduction requires multiple proton-coupled electron transfers, resulting in a range of carbon intermediates (C1-C3) as well as a larger amount of H2 over CO2 conversion products.
For the realization of solar CO2 recycling, the system of interest should be operated sustainably, which requires the development of not only energy-efficient and cost-effective materials but also stand-alone, complete reaction processes (CO2 reduction and water oxidation) operating for long periods without any external bias. A range of semiconductors (mostly p-types) have been studied for CO2 conversion, including GaP, InP, GaAs, Si, Cu2O, and CuFeO2, all of which have narrow bandgaps (Eg) and sufficient Fermi levels (EF) capable of reducing CO2. Although promising, these materials inherently require potential biases to drive the CO2 reduction reaction and compete with other metallic electrodes, whereas complete reactions (CO2 reduction and water oxidation) have been rarely demonstrated due to large overpotentials. Photocathode-photoanode couples have been demonstrated to operate, yet the syntheses of materials are complicated and the energy conversion efficiency is low.
Solar conversion of carbon dioxide and water to value-added chemicals remains a challenge. A number of solar-active catalysts have been reported, but they still suffer from low selectivity, poor energy efficiency, and instability, and fail to drive simultaneous water oxidation.